Tube and machining device and method for manufacturing the same

ABSTRACT

A machining device used to machine a workpiece into a tube includes a punch and a cavity die. The cavity die includes a cavity and an extruding portion. The extruding portion is curved. The unilateral clearance between the punch and the cavity die is less than a thickness of the sidewall. A method for manufacturing a tube is also provided.

BACKGROUND

1. Technical Field

The present disclosure generally relates to a tube and a machining device and a method for manufacturing the same.

2. Description of Related Art

Recently, drawing dies are widely used to form tubes.

However, the drawing process easily causes stress concentrations. Thicknesses of a tube formed by a drawing die from a top portion to a bottom portion are different, with a sidewall at the top portion being the thickest and a connecting portion between the sidewall and a bottom wall being the thinnest. Thus, the connecting portion may be fractured when the tube is continuously and excessively drawn. Ratios of height to width of the tube are accordingly limited to within 9:1, especially when an angle formed by the bottom wall and the sidewall requires tapering, where the height to width ratio of the tube is limited to within 6:1. Accordingly, when the height to width ratio of a tube exceeds 9:1 and when the angle formed by the bottom wall and the sidewall requires tapering, welding is employed to attach two or more parts together.

The tube formed by such welding may exhibit welding seams or marks, affecting the exterior appearance of the tube.

Thus, a tube, machining device and a method for manufacturing the same are desirable to overcome the described limitations.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views, and all the views are schematic.

FIG. 1 is a schematic cross-section of one embodiment of a workpiece.

FIG. 2 is a schematic cross-section of one embodiment of a machining device shown with the workpiece in FIG. 1 not yet machined.

FIG. 3 is a schematic cross-section of the machining device of FIG. 2, shown with the workpiece having been machined.

FIG. 4 is a flowchart of one embodiment of a manufacturing method of the machining device in FIG. 3.

FIG. 5 is a schematic cross-section of one embodiment of a tube formed from the workpiece in FIG. 1 by the machining device in FIG. 2.

DETAILED DESCRIPTION

Referring to FIG. 1, one embodiment of a workpiece 10 includes a sidewall 13, a bottom wall 14, and a slot 11 enclosed thereby. The workpiece 10 can be made of aluminum formed by forging and backward extrusion. Alternatively, the workpiece 10 may also be made of steel or other metallic material.

Referring to FIG. 2, one embodiment of a machining device 50 includes a punch 20 and a cavity die 30. Unilateral clearance A between the punch 20 and the cavity die 30 is less than a thickness B of the sidewall 13. In the illustrated embodiment, the unilateral clearance A is less than the thickness B by about 0.35 millimeters (mm) to about 0.5 mm.

The cavity die 30 includes a cavity 31 and an extruding portion 32. The extruding portion 32 is curved with a radius not less than the difference between the thickness B of the sidewall 13 and the unilateral clearance A to prevent the workpiece 10 from fracturing during extruding.

Two unloading subassemblies 33 are positioned on one end of the cavity die 30 away from the extruding portion 32, at opposite sides of the cavity 31. Each unloading subassembly 33 includes an unloading member 37 and an elastic member 35 resisting the unloading member 37. In the illustrated embodiment, the elastic member 35 is a compression spring. An end of the unloading member 37 away from the spring 35 forms a resisting portion 38 protruding adjacent to an edge of the cavity 31. The resisting portion 38 includes a guiding surface 381 and a planar surface 383 opposite to each other. The guiding surface 381 faces the cavity 31, such that the workpiece 10 passes through the unloading subassemblies 33. In the illustrated embodiment, the guiding surface 381 is curved. The guiding surface 381 of the resisting portion 38 can be angled or any other shape that would facilitate the workpiece 10 sliding to resist the unloading member 37 and compress the elastic member 35.

Referring to FIGS. 2 through 4, one embodiment of a method of manufacturing a tube includes providing the workpiece 10 and the machining device 50, sleeving the workpiece 10 on one end of the punch 20 of the machining device 50, with the punch 20 and the workpiece 10 moving towards the cavity 30. As the workpiece 10 resists the extruding portion 32 of the cavity die 30 and continues to move downwards, the sidewall 13 is extruded to a thickness equal to a unilateral clearance A. Reduced material on the transverse direction of the sidewall 13 moves in the longitudinal direction of the punch 20 to coat the punch 20. During the action of the punch 20 and the workpiece 10, the workpiece 10 resists the guiding surface 381 of each unloading member 37, and slides each unloading member 37 to compress each corresponding elastic member 35. As such, the workpiece 10 passes through the resisting portion 38 of each unloading member 37, and a tube 15 is formed. The elastic members 35 of the unloading subassemblies 33 rebound to return the unloading member 37 to resist the punch 20. As the punch 20 moves out of the cavity die 30, the tube 15 is removed from the punch 20 by the planar surface 383 of the unloading member 37 generating force on the tube 15, which is unloaded accordingly.

Referring to FIG. 5, the tube 15 as disclosed includes a sidewall 18, a bottom wall 19, and a slot 17 enclosed by the sidewall 18 and the bottom wall 19. To meet the required ratio of height H to width B for the tube 15, the workpiece 10 can be machined several times. The tube 15 is formed by the machining device 50 such that reducing material on the transverse direction of the sidewall 13 moves along the longitudinal axis of the punch 20 to increase the height H, and during machining of the workpiece 10 into the tube 15, stress concentration is avoided. The ratio of the height H to the width D of the tube 15 can exceed 9:1, even when an angle θ formed by the bottom wall 19 and the sidewall 18 requires tapering, in which case the height to width ratio of the tube can exceed 6:1.

Finally, while various embodiments have been described and illustrated, the disclosure is not to be construed as being limited thereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the appended claims. 

1. A machining device machining a workpiece comprising a sidewall, the machining device comprising: a punch; and a cavity die, comprising: a cavity; and an extruding portion; wherein the extruding portion is curved and a unilateral clearance between the punch and the cavity die is less than a thickness of the sidewall of the workpiece.
 2. The machining device of claim 1, wherein the unilateral clearance between the punch and the cavity die is less than a thickness of the sidewall by about 0.35 mm to about 0.5 mm.
 3. The machining device of claim 1 further comprising at least one unloading subassembly positioned at an end of the cavity die away from the extruding portion, wherein the at least one unloading subassembly comprises an unloading member and an elastic member resisting each other, and the unloading member resists the punch by an elastic force of the elastic member.
 4. The machining device of claim 3, wherein the at least one unloading subassembly comprise two unloading subassemblies, each unloading subassembly positioned on one end of the cavity die away from the extruding portion, and at opposite sides of the cavity.
 5. The machining device of claim 4, wherein the unloading member forms a resisting portion comprising a guiding surface facing the cavity to facilitate the workpiece sliding through the unloading subassembly.
 6. The machining device of claim 5, wherein the guiding surface of the resisting portion facing the cavity is curved.
 7. The machining device of claim 6, wherein the resisting portion further comprises a planar surface opposite to the guiding surface.
 8. A method of manufacturing a tube, the method comprising: providing a workpiece comprising a sidewall; providing a machining device comprising a punch and a cavity die, the cavity die comprising a cavity and a curved extruding portion, a unilateral clearance between the punch and the cavity die being less than a thickness of the sidewall of the workpiece, and the workpiece sleeved on the punch; and impelling the workpiece towards the cavity die via the punch, wherein the sidewall is extruded to a thickness equal to the unilateral clearance by the extruding portion, and the reducing material on the transverse direction of the sidewall moves along a longitudinal axis of the punch to increase the size along the longitudinal axis of the workpiece.
 9. The method for manufacturing a tube of claim 8, wherein the workpiece is formed by forging and backward extrusion.
 10. The method for manufacturing a tube of claim 8, wherein the unilateral clearance between the punch and the cavity die is less than a thickness of the sidewall by about 0.35 mm to about 0.5 mm.
 11. The method for manufacturing a tube of claim 8, further comprising an unloading subassembly positioned at an end of the cavity die away from the extruding portion, wherein the unloading subassembly comprises an unloading member and an elastic member resisting each other, and the unloading member resists the punch by an elastic force of the elastic member.
 12. The method for manufacturing a tube of claim 11, further comprising another unloading subassembly, both unloading subassemblies positioned on one end of the cavity die away from the extruding portion and at opposite sides of the cavity.
 13. The method for manufacturing a tube of claim 12, wherein the unloading member forms a resisting portion comprising a guiding surface facing the cavity to facilitate the workpiece sliding through the unloading subassembly.
 14. The method for manufacturing a tube of claim 13, wherein the guiding surface of the resisting portion facing the cavity is curved.
 15. The method for manufacturing a tube of claim 14, wherein the resisting portion further comprising a planar surface opposite to the guiding surface.
 16. A tube, comprising: a sidewall; and a bottom wall; wherein the tube is formed by extruding a single workpiece, the height to width ratio of the tube exceeds 9:1 or the height to width ratio of the tube exceeds 6:1 when an angle formed by the bottom wall and the sidewall of the tube is a taper angle. 